Supplementary controlled draft for fuel burners



M 30 1937 c. v. MARTIN 2,199,547

SUPPLEMENTARY CONTROLLED DRAFT FOR FUEL BURNER S 1 Filed Nov. 5, 1934 ZSheets-S'neet l Nov. 30,1937. I c. v. MARTIN 2,100,547

SUPPLEMENTARY CONTROLLED DRAFT FOR FUEL BURNERS Filed Nov. 3, 1934 2 SheetsSheet 2 v ii 14 Patented Nov. 30, 1937 UNITED STATES SUPPLEMENTARY CONTROLLED DRAFT FOR FUEL BURNER S Clarence Verne Martin, Toledo, OhioQassighor to The National Supply Company, Pittsburgh, Pa., a, corporation of Pennsylvania Application November 3, 1934, Serial-No. 751,371

. 2 Claims.

7 This invention relates generally to the control of supplementary air for fluid fuel burners for steamboilers and more specifically to the control of steam jet supplementary air boosters.

' This-invention may be advantageously applied to steam generating devices wherein the control of the supplementary air to the burning fuel is overned-by generated steam of the boiler under constant pressure irrespective of the steam load being furnished. Such a' device is disclosed in' IIettersPatentNo. 135K828, issued May 13, 1930. It is'a wellk-nown fact that full losses in any fuel burning system are caused" by either overventilatio'n'or underventilation. When an excessive demand'is made upon the steam generating system, more fuel and more air are naturally required to producemoi'e steam. While it is possible to maintain a proper relation between the fuel and the air' under normal conditions, itis sometimes diflicult to do so when excessive demands for steam are imposed upon the system. When insufiicient air is' supplied to properly support combustiona portioni'of the'unburnedproductspass outof the stack in the form of. carbon monoxide alongwithi the flue gases; .An increased supply of oxygen in' thecombus'tion chamher will convert carbon'm'onoxid'einto carbon'dioxidelformin'g. a complete: product of combustion.

Boilers designedxto'operate under automatic control depend upon .the natural draft of: the boiler stack to draw the air into the combustion chamber to mix with the fluid fuel being burned. The. draft providedaby the stack is. not sufficient to properly support the combustion of .the increased volume of fuel demanded by reason of a sudden increase in the load of steam reducing the boiler pressure.

Such an increase in the steam load which causes the reduction of the boiler pressure will operate the fuel and air valves and increase the combustion but it islimitedby-reason of thenatural stack draft of the boiler. In locomotive art this is corrected by providing an exhaust steam jet in the stack to-increase the flue draft; but in the instance ofthe application thisis impractical besaid combustion chamber.

Another. object is toprovide forcontrolling .the staclcdraftfl of a boiler concurrently with the control of supplementary air intake.

Another object isto provide means for controlling a. steam jet in the stack of a boiler by the operation .of a draft valve which is automatically regulated by the steam pressure within the boiler.

Other advantages and objects will the following description. i v

In the accompanying drawings whereinI'have illustrateda practical embodiment of the prin-j ciples of my invention, Fig. 1 is aside elevation of a boiler illustrating the application of'my de- Vice thereto. 1 V s Fig. 2 is a top plan view of the damper valve appear in construction showing my steam jet control valve 3,0

applied thereto. 7 V r a Fig. 3 is a side elevation of thedamper box and the controls therefor illustrating the application of my control valve thereon. I

Fig. l'isan enlarged sectional view taken longitudinally of my control valve illustrating'the'oper-f ative connection thereof with the damper valve parts being broken away. t I I Fig. 5 is a sectional view taken onthe line 5- -5 ofFig;4. V 5

Referring to'iFigs. 1" to 3'of the-drawings, l0 represents a boiler having a stack l l and a steam dome i2. I3 represents a fuel burner unit which is provided with burners positioned; within the combustion chamber of the boiler and fed by the fuel line 14. The flow of the fuel is determined by'the vacuum controlled regulator'l5 which is placed in the fuel supply line between the burner valvelfiandthe gate valve ll. [8 is a fuel strainer housing which is placed in the fuel line between the gate valve I! and the fuelsupply line l4. 2!!

represents the pilot burner control line which is tapped into the fuel supply line ahead of the regulatorg,

2! represents the opening of the vertical air supply conduit 22 which is connected to one end of the horizontal conduit 23, the other end of which opens into the combustion chamber under the burners.

24 represents a rectangular butterfly damper valve arranged to control the opening of the conduit 7 22; and consequently the air passing therethrough. This valve is supported at each end by the members 25 and 26 having the knife edges 21 resting in the bearing grooves 28 sup.- ported on the sides of the vertical conduit 22.

29 represents a damper motor which is provided with a flexible diaphragm connected to the damper valve 24 by means of the arm 30 for operating the same. The. damper motor is provided with a pressure chamber above the diaphragm which is connected by the pipe line 3| to the fuel burner pressure chamber below the diaphragm of the fuel regulator [5. The chamber above the diaphragm of the regulator is a vacuum chamber which is providedwith the exhaust pipe line 32 connected to the boiler governor 33 mounted on top of the steam dome 12. The structure and operation of the steam governor and the regulator is described in the above mentioned Letters Patent.

,'I'hus the steam governor 33, which is controlled by the steam pressureof the boiler, operates the regulator I5 which in'turn controls the amount of fuel to the burners and the pressure of thisfuel, which is a direct function of the volume of the fuel delivered to the burners, operates the damper motor 29 which controls the degree of the opening of the butterfly valve 24 in'proportion to the amount of fuel delivered to the burners. Y a

This apparatus operates on small differences in pressure but the apparatus controlling. the air to the combustion chamber does not furnish an adequateamount of air to supply the need of the burning fuel because the draft through the combustion chamber to the stack is .not adequate to carry the volume of air required for burningthe increased amount of fuel. This re: sults inunderventilation until the draft builds up and during this period the unburned fuel passes out thestack which lowers the efficiency of the boiler.

Again, excessive demands for increased steam pressure which increase the amount of fuel required'often exceed the capacity of the stack to develop a sufficient draft to supply the proper amount of oxygen for combustion. .This sometimes is due to the physical location of the boiler and sometimes the weather conditions.

To avoid these dimculties and'to provide sufficient oxygen to the combustion chamber I provide the steam jet 34 within the stack H to create-an increased draft which increases the volume of air drawn through the combustion chamber.-

The jet 34 is supplied with steam through the pipe35 which is connected to the steam control valve 36. The other side of the valve is connected to the steam dome I2 through the pipe 31.

The steam valve comprises the casing 38 which -in this instance is an integral part of the bearing member 28 supported by the fuel burner unit frame member on the side of the vertical conduit 22. The 'casingis bored out as at-39 to receive the cylindrically shaped rocker valve plug 40. The axis of the valve 40 is the same that ,of the knife edge il of the member 25,

The inner end of the valve 40 is provided witlff a verticallydisposed transverse lug 4| arranged to be operatively received within the bifurcated end 42 of the member 25.

Adjacent the outer end of the valve 40 the casing 38 has secured thereto a cap or closure grease cup 48 through the stopcock 49 and the passageway 50. I The grooves 41 receive their lubrication through the longitudinal slot 5| in the casing 38 which connects the passage 50 to said grooves.

Intermediate of the grooves the valve 40 is provided with the port 52 disposed horizontally and transversely through the diameter thereof when the valve is in its open position, as shown in Figs. 4 and 5. 'In this position the ends of the port 52 are arranged to register with their corresponding openings in the casing 38 which com nect the steam lines 35 and 31.

Thus when the butterfly damper valve 24 hasbeen rotated from its position as shown in dotted lines in Fig. 3 to the vertical position shown in Fig. 4 the member 25 causes the valve 40 to rotate so that the port 52 is fully open and permits steam to pass therethrough.

When the steam pressure of the boiler has been diminished sufficiently to decrease the vacuumsv created by the governor 33 the regulator l5 will operate to admit more fuel to the burners "This creates a greater pressure in the fuel side of the regulator which becomes effective inthe damper motor 29 throughthe pipe 3| to open the damper as the volume of the fuel being fed to the burners is increased. The movement of thedamper valve 24 operates the steam valve 40 to permit steam to exhaust through'thejet 34 in the stack, thereby 7 creating sufficient air draft through the combustion chamber to obtain complete combustionof the increased volume of fuel.

The degree of operation of the air .valve24 is 7 determined by the steam pressureand this valve invention, the object in view being to produce by means of the steam jet the desired draft in the combustion chamber.

The term supplementary air as used herein designates the additional air supplied to the combustion system in excess of that possible to be supplied by natural draft sources.

1. In apparatus for controlling a draft inducing stack jet in a fluid fuel fed boiler, the combination of a boiler governor actuated in response to the steam demand on said boiler, a regulator operated by said governor for controlling the pressure of the fuel fed to said boiler, and valvular means operated by the pressure of the fuel for controlling the amount of steam fed to the stack the pressure of the fuel fed to said boiler, a

jet. damper for controlling the air fed to said boiler,

2. In apparatus for controlling a draft ina motor operated by said fuel pressure for actuducing stack jet in a fluid fuel fed boiler, the ating said damper, and valvular means actuated 5 combination of a boiler governor actuated in reby the movement of the damper for controlling 5 sponse to the steam demand on said boiler, a regthe amount of steam fed to the stack jet. ulator operated by said governor for controlling CLARENCE VERNE MARTIN. 

